Sludge scraper for sedimentation basins



Mmh 3, 1970 a. HOLLEBRANDT I 3,498,467

SLUDGE SCRAPER FOR SEDIMEN'I'ATION BASINS 5 Sheets-Sheet 1 Filed Jan. 16, 1969 INVEN'IOI ERHARD HOLLEBRANDT BY 7/01" ATTORNEYS March 3, 1970 E. HOLLEBRANDT SLUDGE SCRAPER FOR SEDIMENTATION BASINS 5 Sheets-Sheet 2 Filed Jan. 16, 1969 INVEN'IOR ERHARD HOLLEBRANDT BY 3 7 25 ATTORNEYS March 3, 1970 a. 'HOLLEBRANDT 3,

SLUDGE SCRAPER FOR SEDIMENTATION BASINS Filed Jan. 16, 1969 5 Sheets-Sheet 3 ERHARD HOLLEBRANDT ATTORNEYS March 1970 E. HOLLEBRANDT 3,

SLUDGE SCRAPER FOR SEDIMENTATION BASINS Filed Jan. 16, 1969 5 Sheets-Sheet 4 mvsmon ERHARD HOLLEBRANDT ATTORNEYS March 3, 1970 E. HOLLEBRANDT SLUDGE SCRAPER FOR SEDIMENTATION BASINS s Shets-Sheei: 5

Filed Jan. 16, 1969 INVENTOR ERHARD HOLLEBRANDT Q nY; 2;s9% c2 /sy ATTORN EYS United States Patent 3,498,467 SLUDGE SCRAPER FOR SEDIMENTATION BASINS Erhard Hollebrandt, Michelbacherhutte, Germany, assignor to Passavant Werke, Michelbacherhutte, Germany, a corporation of Germany Filed Jan. 16, 1969, Ser. No. 791,740 Int. Cl. B01d 21/06, 21/04 U.S. Cl. 210-527 16 Claims ABSTRACT OF THE DISCLOSURE A sludge scraper device for a sedimentation basin. The scraper is pivotally connected to a laterally movable scraper bridge for movement into and out of the basin. The blade is raised to a position above the upper rim of the basin by its engagement with stop members mounted on the basin during part of the lateral movement of the bridge.

BACKGROUNDFIELD OF THE INVENTION This invention relates to sewage apparatus; and in particular it relates to a sludge scraper for a sedimentation basin.

BACKGROUNDDESCRIPTION OF THE PRIOR ART It is known to provide, for use with sedimentation basins, a sludge scraper having a scraper blade mounted on a movable bridge and capable of being lifted out of the basins both for cleaning and for transferring the blades to other basins, whereby the same scraper blade is used for a plurality of basins. However, heretofore, it was necessary to provide, in addition to the scraper blades, lifting equipment such as winches, electric motors, etc., normally mounted on the bridge, for lifting the scraper blades. This additional equipment added complexity and expense to the apparatus.

SUMMARY OF THE INVENTION Thus, it is a purpose of this invention to provide a sludge scraper arrangement wherein the need for additional lifting equipment is eliminated.

In accordance with the present invention, the scraper blade is pivotally connected to the bridge and there is provided at least one stop member located above the upper rim of the basin, this stop member being arranged such that as the bridge moves laterally above the basin, the scraping blade engages the said stop member and is moved upwardly thereby to a level above the upper rim of the basin.

In a preferred embodiment of the invention, a locking device is provided for holding the scraping blade in its said raised position. The scraping bridge can then be manipulated, with the scraping blade in its raised position, laterally, back and forth over the basin and also from one basin to the next. In accordance with another feature of the invention, the apparatus may include a damping means for delaying the lowering of the scraping blade into the basin. Examples of such damping means includes a hollow floating portion attached to the scraping blade so that the buoyancy thereof will delay the lowering, a downwardly open bell-shaped member attached to the scraping blade and having small openings in its upper portion for limited airflow therethrough, Whereby the air trapped under the bell-shaped profile during downward movement of the scraping blade escapes slow- 1y through the said upper openings. Further, the apparatus may include a pneumatic or hydraulic damping de-v vice or a friction coupling brake connected between the 3,498,467 Patented Mar. 3, 1970 bridge and the scraping blade for limiting the downward movement of the latter.

Contrary to the prior art, where the lifting force was applied directly by lifting equipment, in the present case the lifting force is that required to move the bridge laterally this force being transferred to the bridge drive means through the bridge, the wheels of the bridge and the friction between the wheels and the rails on which the bridge is mounted. Consequently in order to minimize the lifting force, the invention may include a plurality of stop members arranged at diiferent vertical levels, the scraping blade being designed such that it cooperates with the stop members so that during the lifting procedure the stops are engaged in subsequent periodic sequence from the lowermost stop member upwardly. Preferably at least one of the stop members is positioned lower than the upper rim of the basin.

The distribution of the lifting forces can be further enhanced by providing the scraping blade with a downwardly concave portion and arranging at least one stop member to engage this portion. By properly designing the contour of the said downwardly concave portion, it is possible that the angle of inclination of the surface actu ally engaging the stop member remains substantially constant as the scraping blade moves over the stop member.

In another arrangement for distributing the lifting forces, a stop member may be provided at one end of a lever arm, which lever arm is pivotally connected with a wall of the basin at its other end. The scraping blade includes a coupling portion for positively engaging the said stop member. With this arrangement, after the scraping blade engages the said stop member the lever arm is swung upwardly and thereby automatically and promptly lifted above the upper rim of the basin. In this arrangement the stop member functions as a crank drive.

According to another feature of the invention, forces can be reduced by designing the stop members with rolling means or the like for reducing friction.

Thus, it is an' object of this invention to provide a rgew and improved scraping blade for a sedimentation asln.

It is another object of this invention to provide a scraping apparatus for a sedimentation basin which does not require the use of additional equipment for lifting the scraping blade.

It is another object of this invention to provide a scraping apparatus having a self-raising scraping blade and including means for evenly distributing the forces required to lift the scraping blade.

It is another object of this invention to provide a scraping apparatus for a sedimentation basin including damping means for damping the lowering movement of the scraping blade into the sedimentation basin.

Other objects and the attendant advantages of the present invention will become apparent from the detailed description to follow, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS A There follows a detailed description of a preferred embodiment of the invention to be read together with the accompanying drawings. However, it is to be understood that the description and the accompanying drawings are provided solely for purposes of illustration, and that the invention is capable of numerous modifications and variations apparent to those skilled in the art without departing from the spirit and scope of the invention.

FIGURE 1 is a vertical section view taken through a sedimentation basin and showing a sludge scraping apparatus constructed in accordance with the features of the present invention.

FIGURE 2 is a vertical sectional view similar to 3 FIGURE 1 but showing a modified arrangement of the sludge scraping apparatus.

FIGURES 3 and 4 show front and side views, respectively, of a friction coupling arrangement for use with the apparatus of the present invention.

FIGURE 5 is a diagrammatic illustration showing a number of sedimentation basins adapted for use with the movable scraping apparatus of the present invention.

FIGURE 6 is an enlarged partial view of a portion of FIGURE 2.

FIGURE 7 is a vertical sectional view similar to FIGURE 1 but showing a modified form of the invention.

FIGURE 8 is a vertical sectional view similar to FIGURE 1 but showing another modification of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, like numerals are employed to represent like elements throughout.

FIGURE 1 shows a sedimentation basin indicated generally by the numeral 1, and including an essentially horizontal sole portion 1a and a sludge sump portion 1b arranged at one end into which sump the sludge is conveyed by the scraping attachment 3 which is attached to the scraping blade 2.

The scraping blade 2 is operatively connected to the scraping bridge 4, turning or pivoting movement about the axis 7. The scraper bridge also includes a locking device 5 for retaining the scraping blade in the raised position. The specific details of the locking device 5 are known per se. The bridge 4 is mounted on wheels for lateral movement above the upper rim of the sedimentation basin (from right to left as shown in FIGURE 1).

In the embodiment of FIGURE 1, there is provided, for raising the scraping blade 2, a pair of stop members 6a and 612. These stop members cooperate with the lower surface of the scraper blade 2 for raising the scraper blade as the bridge 4 is moved laterally to the left (as shown in FIGURE 1). The section of the scraper blade cooperating with the stop members is indicated by the numeral 2a in FIGURE 1 and in this embodiment this portion is straight.

Also illustrated in FIGURE 1 is a pneumatic piston 10 connected at one end to the bridge and at its other end to the scraping blade 2a. This pneumatic piston is designed to act as a damping means for delaying the lowering movement of the scraping blade. Also illustrated in FIGURE 1 is another stop member 8, located at the forward end of the. sedimentation basin. This stop member 8 is provided to cooperate with the locking device 5 for releasing the scraping blade 2 when the bridge 4 has moved to the forward end of the sedimentation tank.

The embodiment of FIGURE 1 operates as follows. Initially, the scraping blade 2a is retained in the raised position above the upper rim of the sedimentation basin by the locking device 5 as shown at 2a and 3a, in phantom lines, in FIGURE 1. In this condition the bridge 4 is moved to the right (as shown in FIGURE 1) until the attachment 3 has just about reached the front abutment 9. At this point the stop member 8 releases the scraping blade 2 from the locking device 5. The scraping blade 2 then falls downwardly into the sedimentation basin 1. This lowering movement is delayed by means of the pneumatic piston 10. The bridge 4 then moves slowly to the left as the attachment 3 of the scraping blade 2a moves along the bottom of sole portion 1a scraping sludge into the sump 1b. Finally, at the completion of the scraping operation, the elements reach the position shown in solid lines in FIGURE 1. At this time the portion 2a of the scraping blade engages the stop :member 6a. Further movement to the left of the bridge 4 causes the scraping blade 2 to be raised upwardly. The scraping blade is shown at 2a" at the point where the upper part of the scraping blade engages the upper stop member 6b which is located at the level of the upper rim of the sedimentation basin. Further movement to the left of the bridge 4 causes the scraping blade 2a to complete its upward movement to the. position 201", as shown in FIGURE 1. At this time the scraping blade 2 is retained by the locking device 5. It can be seen that the section 2a engages stop member 6a with a steep angle of inclination. Then, in the intermediate position 2a" the section 2a engages the stop member 6b above the upper rim of the basin and the lower part of scraping blade 2 engages the stop member 60 but at a smaller angle of inclination.

FIGURE 2 shows a modified form of the invention wherein the sedimentation basin 1 has a single stop member 60 and the portion 2b of the scraping blade 2 which engages the stop member 60, has a downwardly concave curvature. During the leftward movement of the bridge 4, after the scraping blade 2 has engaged the stop member 6c the scraping blade 2 is raised upwardly while the angle of inclination of the section 2b at the stop member 6:: remains substantially constant. This occurs, of course, only until the straight part of scraping blade 2 engages the stop member 60 at which time the scraping blade 2 will be in its raised position and held by the locking device 5 as shown in dotted lines in FIGURE 2.

FIGURE 2 shows a modified damping means. Instead of the pneumatic damping means 10, the attachment 3 is replaced with a different attachment 3a in the form of a bell having an open bottom. This feature is also shown in FIGURE 6 in greater detail. The upper part of this bell-shaped attachment is provided with small air discharge openings 12. During lowering of the scraping blade 2, that is after the attachment has entered the liquid in the basin, the air accumulated in the bellshaped attachment can only escape through the openings 12. These openings are sufliciently small so that the escape of gas is limited and hence the lowering of the scraping blade is slowed down.

FIGURES 3 and 4 show another damping means which may be employed to slow the downward movement of the scraping blade 2. This arrangement includes a pair of flange members 16 mounted on shaft 7a which is an extension of shaft 7. A friction disc 17 connected to the bridge 4 is located between the flange members 16. A spring 18 urges the flange members together and against the friction disc 17 while a nut 19 is provided for adjusting the force of the spring 18. A safety device is also provided for connecting the flange member 16 to the shaft 711. This includes a toothed wheel 14 fixed on the shaft 7a and a latch 15 connected to one of the flange members 16.

As is evident from FIGURE 4, upon downward movement of the scraper blade 2 (clockwise movement of the members 7a, 14 and 16 as shown in FIGURE 4) a positive engagement is provided between the elements 14 and 16, and hence between the flange members 16 and the shaft 7a. However, when the scraping blade 2 is raised, the shaft 7a turns counterclockwise (as shown in FIG- URE 4) and hence the teeth of wheel 14 pass beneath the latch member 15. 7

FIGURE 5 shows the bridge of the present invention in combination with a plurality of side-by-side sedimentation basins 1. The scraper bridge 4 will travel along platform 13 on rails 13a to be transferred from one basin to the next.

FIGURE 7 shows still another modification of the invention. In this embodiment a stop member 6d engages the scraping blade 2 and follows a circular path carrying the scraping blade upwardly to its raised position. The stop member 6d is fixed on one end of a lever-arm 24, which arm is pivotally connected at its other end 23 to the wall of basin 1. There is also provided a fixed stop member 21 to limit the downward movement of arm 24 about its axis 23. In operation, as the bridge 4 is moved to the left, a V-shaped coupling piece 22 on the scraping blade 2 engages the movable stop member 6d. Upon further movement of the bridge 4 to the left, and because of the positive engagement between the stop member 6d and the scraping blade 2, the scraping blade 2 is turned rapidly in the counterclockwise direction about its pivot axis 7 as the stop member 6d follows the circular path as shown in dotted lines in FIGURE 7 about pivot axis '23. Finally, the scraping blade reaches its uppermost position as shown in dotted lines in FIGURE 7 above the upper rim 1c of the sedimentation tank 1.

FIGURE 8 shows still another embodiment of the invention. This embodiment is similar to the embodiment of FIGURE 1 in that two stop members 6a and 6b are provided. Here, however, the lifting forces are further reduced by raising the pivot axis 7 to the level 7b as shown in FIGURE 8. With this arrangement, it is apparent that the top arm of the two sections of the lever on opposite sides of the stop member are divided more evenly so that the force required to lift the scraping blade 2 is reduced.

Although the invention has been described in considerable detail with respect to preferred embodiments thereof, it will be apparent that the invention is capable of numerous modifications and variations apparent to those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. A sludge scraper for a sedimentation basin comprising, a scraping blade, a scraping bridge mounted for lateral movement above the basin, said scraping blade pivotally connected to said scraping bridge for lateral movement therewith and for swinging movement relative thereto between a raised position whereat the scraping blade is located above the upper rim of the basin, and a lower position whereat the scraping blade enters the basin for performing the sludge scraping operation, abutment means cooperating with the scraping blade during movement of the latter for causing upward movement of the scraping blade from said lowerposition to said raised position, the last said meanscomprising at least one stop member located above the upper rim of the basin and positioned to be engaged by the scraping blade during a portion of the movement thereof with the scraping bridge.

2. A sludge scraper according to claim 1, wherein, in the raised position, the entire scraping blade is located above the rim of the basin.

3. A sludge scraper according to claim 2 including a locking device operatively associated with said bridge for holding the scraper device in the said raised position.

4. A sludge scraper according to claim 1 including a damping means for delaying the movement of the scraper blade from said raised position to said lower position.

5. A sludge scraper according to claim 4, wherein said damping means comprises a closed hollow body connected to the scraper blade for movement therewith into the basin in said lower position, said body causing a buoyant force to be exerted on the scraper blade in the basin.

6. A sludge scraper according to claim 4, wherein said damping means comprises a downwardly open bellshaped member connected to said scraper blade for m0vement therewith into the basin in said lower position, the upper part of the bell-shaped member having openings therethrough for limited air flow therethrough.

7. A sludge scraper according to claim 4, wherein said damping means comprises a pneumatic damping device operatively connected to said scraper bridge and said scraper blade.

8. A sludge scraper according to claim 4, wherein the scraping blade is mounted on a shaft rotatable about said pivot axis, and said damping means comprises a friction brake connection between the scraper bridge and the said shaft of the scraper blade.

9. A sludge scraper according to claim 1 wherein said abutment means comprises at least one further stop member located below the first said stop member.

10. A sludge scraper according to claim 9 wherein the section of the scraper blade which cooperates with the stop members is shaped such that during said portion of the lateral movement of the bridge, the scraping blade engages the stop members in subsequent periodic sequence from the lowermost stop member upwardly.

11. A sludge scraper according to claim 9 wherein the said further stop member is below the upper rim of the basin.

12. A sludge scraper according to claim 1 wherein the section of the scraper blade which cooperates with the said at least one stop member is concave towards the said stop member.

13. A sludge scraper according to claim 9 wherein the said at least one stop member is mounted for movement from a position within the basin to a position at least as high as the rim of the basin.

14. A sludge scraper according to claim 13 including a lever-arm pivotally mounted on a wall of the basin, said movable stop member being connected to the end of the lever-arm opposite from its connection with the basin wall, and means on the scraping blade for coupling the same with the movable stop member, whereby upon further movement of the scraping blade with the bridge after coupling of the stop member and the scraping blade, the scraping blade is automatically raised to said raised position.

15. A sludge scraper according to claim 1 wherein said at least one stop member includes an anti-friction rolling surface.

16. A sludge scraper according to claim 1 including, in combination, a plurality of said basins arranged sideby-side, a platform arranged alongside all of said plurality of basins, said bridge being mounted for movement on said platform to positions adjacent each of said plurality of basins and for said lateral movement over each of said plurality of basins.

References Cited FOREIGN PATENTS 510,264 7/1939 Great Britain.

JAMES L. DECESARE, Primary Examiner 

